Automatic electric control mechanism



Aug. 31, 1937. H. sMlTx-IWICK- AUTOMATIC ELECTRIC CONTROL MECHANISM INI/ENTOR Filed Oct. 8, 1928 II Y WITNESS l W76 Patented Aug. 31, 1937 PATENT OFFICE 2,091,111 u AU'roMA'rIC ELECTRIC CoNraoL Macu- ANIsM Harold Smithwlek,

Scandale,

N. Y., assignor, 'by

mesne assignments, to The Raymond Bag Company, a' corporation of Ohio I Application October 8,

192s, sci-iai No. 311,143

24 claims. (Cianmy This invention relates to automatic electric control mechanism, and more particularly to a control mechanism involving the use of a photoelectric cell in combination with an amplifier by s, means of which the passage of a ray of light to the cell, or the interruption of such passage, may be used to influence or control another mechanism and thus regulate the operation thereof.

In its broader aspects my invention contemplates the utilization of a photo-electric cell in association with a source of a ray of light, the continuity of which is established or interrupted by the presence or absence of any definite condition or object at any predetermined time or place. The current generated in the photo-electric cell, or the breaking of such current, is made to operate or control a machine or mechanism designed to affect, alter or influence said condition or object in a predeterminedmanner, or

else perform an operation at a point removed from the locale of such condition or object The current generated by the cell is preferably first greatly amplified and is then made to control the machine or mechanism either'directly or indirectly through a relay.

The inventive idea above outlined may be embodied in a large number of mechanisms and apparatus which themselves, or in which the articles operated upon by them, are normally so designed or colored or may beso modified thatthe continuity, intensity or character of a ray of light may be :altered tomake or break an electric current in a photo-electric cell so as to control the operation of the apparatus with which the cell directly cooperates or of a device only indirectly associated with said cell.

.As an example of the numerous forms thaty my 'invention may take I shall describe the same inV association with a paper-feeding machine, but

understood that my lifnited to such machine. More specifically I shall illustrate my invention in connection with the feeding of a printed web into a machine which subsequently folds, cuts off and otherwise operates on the severedportions of the printed web' to form a finished paper bag,

' It will be readily` understood that in4 making a printed article which is sold in a folded condition, such as a bag; much more elaborate printing on such article may continuous web from which the article is to be made is first printed in its fiat conditionand then wound up on a roll from whichit is subsequently unwound and l-fed to the bag-forming machine.

The printing may be an all-over design or it mayv invention is not be an individual design which recurs at definite intervals along the length of the web; these in' tervals corresponding to the definite lengths to be cut off and made into special articles, such as bags, on each of which the printed designfmust 5 occupya definite position.

While this design may be accurately spaced along the 4web when printed, changes may occur due to change in moisture content or other con-l dition of the printed material; or to inaccuracies 10 or irregularities in the machine in which the printed web is fed and cut off, or to slip of the printed web when being drawn into the machine,

vwhich cause the definitely get out of register with 'the machine and thus 15 cause the printed impression to get into a wrong location on the finished article. Where, for instance, a cutter operated from a constant speed shaft ls arranged to sever portions of the printed web at denite intervals, slipping of the feed rolls.. 20 whereby the feed of the web is slowed down, or shrinkage of the web, the feedsl rolls operating properly to feed a predetermined length during L a definite time interval, whereby the real feed of the web is cutter to lead or lag the web. Such lead orl lag may be very smalland negligible for a single severed section of the web, but if such abnormal vcondition exists for any considerable length of time or for a long stretch of web, the lead or lag will accumulate to such 'an extent that the cutter will sever the web through the printed portions thereof, in which case the articles made from such sections will be practically worthless.

It has been customary to use a manually operated device by which the rolls which draw or feed the printed material into th have their speed changed slightly and ited time without changing the speed of the rest of the achine, such as the cutter, by which arrange ent the web feed may be changed in relarest of the machine and the printed impressions brought again into register, that'is, in their proper position with respect to the cutter. This hand operation has not been altogether satisfactory, among other reasons, because of the labor involved, the unreliability o! the human factor, and because the adjustment of the speed of the feed rolls would necessarily be made only after there had been an appreciable accumulation of lag or lead, and I have therefore devised an electrical control vfor a mechanical web feeding device which I have used successfully as a hand operated mechanism This is the' specific case mentioned in the second paragraph relatively increased, will cause the 25V which will illustrate the electric-control meny tioned in the first paragraph.

I have therefore devised an automatic control mechanism embodying the basic features of my invention and including a source of a ray of light in association with a photo-electric cell which, through the current generated therein, is caused to actuate a. speed control mechanism which operates to speed up the feed rolls when slipping of the web occurs and to slowthem down when the web has shrunk for any reason, so.

that the cutter which operates at constant speed will sever the web along substantially constant and definite lines between the'printed sections thereof and an accumulation of lag or lead to any appreciable extent thereby avoided. It is broadly an object of my invention to provide an automatic controlling mechanism, in-

` cluding a photo-electric cell, which mechanism is regulated by an electric current generated in such cell in response to the incidence of a ray of light thereon.

More specifically, it is an object of the present invention to provide a speed controlling mechanism for paper bag making machines whereby an accumulation of lead or of lag inthe feed of a paper web will be prevented and the web pre- -sented to a cutter at substantially fixed, predetermined points along the length'thereof.

It is a further object of my invention to pro' vide a controlling mechanism of the above-indicated character Which can be associated with existing machines of various types, is simple in construction, and reliable and positive in operation.

Other objects and advantages of my invention will appear from the description hereinafter and the features of novelty will be pointed out in the l claims.

In the accompanying drawing which illustrates a form of my invention without defining its limits, Figure 1 is a plan and Figure 2 is a. side elevation of a paper bag making machine having my .v lengths at 3 by any wellknown means. The

invention embodied therein; and Fig. 3 is a plan view of a portion of the web, showing the relation of the imprints to the apertures.

Referring to the drawing, A indicates a roll of printed paper web from which the web B is drawn over guide rolls over a former I by draw rolls .2 into a tube C which is cut into equal lengths of the tube C cut oil' at 3 are fed by rolls (not shown)y to a cylinder 4.onA which further necessary operations ered lengths.

I have shown only such details of the machine as are necessary for a complete understanding of my invention andhave omitted such details as would serve no useful purpose here and which would only confuse the drawing.

'I'he drive for the machine includes a shaft 5 driven from a pulley 6 mounted thereon. 1 is a gear on the pulley shaft 5 which through an intermediagear s drives gear s keyed to shaft n. 'I'he shaft Il carries the change gear I I which drives the draw rolls 2 through-gears I2 and I3.

I Gear 9 is a sub-multiple of the cylinder gear I5 which it drives through gear I4.l The cutting mechanism located at 3 is so intergeared with shaft I I that a tube length is cut off at each complete revolution of shaft Il. 'Ihe tube length is equal to the circumference of change gear Each tube length cut, regardless of what change gear is in use and of what the consequent length machine X and also at 33. are performed on the sev' of the cut may be is fed to thesame point or points on cylinder 4 where the finishing loperations may be performed.

'I'he web of paper on the roll 4A has been printed by printing cylinders which have a circumference which is equal to or is a multiple or sub-multiple of the circumference of the change gear II. The spacing of the printed impression along the .web should therefore be equal to the circumference of gear I I which is also the length of tube cut off.

'Ihe position ofthe impression on the tube out off is theoretically always in a certain zone between the ends of the tube. In practice it hasA been found that there isa very small amount of slip of the web between the draw rolls 2 and that other factors, such as slightly inaccurate printing, paper shrinkage or possibly wear of the draw rolls 2 may combine to make the printed impression get out of place lengthwise on the tube lengths cut ofi'.

In accordance with my invention, I provide a mechanical device and an electrical control therefor to automatically correct these inaccuracies and to keep the web and tube drawn up in its proper relation to the rest of the machine so that he printed impression will always be in approximately its proper location on the tubes as it is cut off. This is accomplished by means of the following mechanism:

On shaft I0 is keyed the right-hand worm I6 which drives the Worm Wheel I1 on the shaft I8. The shaft I8 drives shaft I9 through miter gears mounted on said shaft. On shaft I9 is keyed a clutch member 20. vOn either side of the clutch member 2I|`are magnetic clutch plates 2| to each of which is fixed a gear, 22 on one and v23 on the other. mounted slip ring connections 22' and 23. Gears, 22 and 23 mesh With gears 24 and 25 fixed on a horizontal shaft 26. Gear 22 meshes directly with gear 24 while gear 23 mesheswith 25 through an intermediate or-idler gear 26'. In'action gears 22 and 24 would drive the shaft 26 clockwise while 23 would driveit counter-clockwise as viewed in Fig. 2. On shaft 26 is also mounted a miter gear 21 which drives a miter gear 28 and a shaft 29 fixed thereto. On shaft 29 is left'hand worm 30 which drives worm gear 3| which is loosely mounted on shaft III. Shaft I0 is in two pieces being cut in two inside of the gear 3| at 32. The longer part has bearings in the frame of the 'Ihe shorter part has one bearingonly in frame'Y. At the sides of worm 3| is a gear 35 fast tothe longer part of shaft I0 and a gear 34 fast to the shorter part of shaft III. Mounted loosely in a bearing in worm -gear 3| is a shaft 36 at the ends ofwhich are fastened gears 31 and 38 which, like gears 34 and 35, are of equal diameter.

At the outer end of shaft- III is keyed a helical gear 39 in mesh with a helical gear 40 which is fast to the end of shaft 4l. On the other end of shaft 4| is gear 42 which drives a gear 43,A the latter being fast to gear 44 which drives gears- 46 and 41 through intermediates 45 and 48. On the same'shaft with 46 and 41 are cylinders 49 and 50 which revolve with their respective gears. Mounted through holes in the cylinders 49 and 50 and extending thereinto are lamps 5I andl 52. Below cylinders 49 and 5II are photo-electric cells 55 and 5,6' of any suitable construction connected to amplifiers 51 and 58. Below the amplifiers are relays 59 and 60. In each relay is hung an armature 6| or 62 whose return to inoperative position On the hub of the clutch plates are .rectly under the centers of is delayed by dashpots having regulators 63 and 64 thereon. On 6I and 62 respectively are insulated plates 65 and 66 on which are contacts which when 5| or 62 is raised close the circuit between connections 61--68 or Bil- 13 and allow the current from the'line to pass through one or the other of the magnetic clutch plates 2|.

The web of paper is punched, preferably when being printed, so as to provide a series of uniformly spaced holes along one edge as at D. The cylinders 49 and 50 are provided with holes 53 and'54 in their surfaces which are arranged to travel in the same vertical lplane as said series of holes in the web. The hole spacing in the web is the same as the spacing of the holes around the circumference of the cylinders, the said circumference being a multiple of the normal distance between adjacent holes in the we The hole spacing in the .web need have no connection with the spacing of the imprints on the paper except that both may be made at the same operation. A conventional form of cutting device is shown at 3 in Fig. 2, and its associated driving mechanism is illustrated in Fig. 1. The cutting device comprises a knife shaft 1|, a knife 12 adjustably clamped in a slot in the shaft by suitable screws. The cned surface of the shaft-13 which carries at the end thereof a gear 14 meshingfwith the gear 15 on the end of the knife shaft 1I. The gear 14 meshes with a gear 16 which in turn is driven by the gear 1.

The operation ofthe above-described mechanism is as follows:

- The machine is started with the printed impressions in such a relation to the draw rolls 2 and the cut-oif at 3'that the impression is properly spaced on the cut-off tube. With the miichine and tube running thus the holes in the paper web are in the relative position shown dicylinders`49 and 50. In this positiony the holes in the cylinders do not register with the holes in the paper. The lower hole 53 of cylinder 49 is just behind the 445V nearest hole in the paperand hole 54 in cylinder 5|! is just ahead of its nearest hole in the paper.

vvWe will now assume that for some reason the paper begins to lag while the machine, including the cutter', continues to run at a uniform speed,

' from right hand worm u will begin to come armature 52.

the drawing rolls 2 being driven from the pulley section of the split shaft I through gears 34, 31, 38, 35, I'I, I2 and I3, the worm wheel 3| being held stationary by the worm 30. Hole 53 in cylinder 49 and its nearesthole in the paper together until they overlap and the light from lamp will shine through hole 53 and the hole in the paper. passing through willstrike the photo-electric cell 55 and will set up an electric current therein which will be built up by the ampliiler 51 to a strengththat will act on the relay 53 to` raise the This will bring the contacts on plate 65 up against terminals 61 and B8 and close the circuit so that the line current of 110 volts will pass through the slip rings 2| on the hub-of the electro-magnetic clutch plate and thus x gear 22 to the member 20 which revolves at all times, being driven counterclockwise (Fig. 2) I6 on shaft I0 through I8 and through the miter gears' to the shaft I9 on which'20 is fixed. When gear 22 is fixed to 23 by the magnetic clutch action, gear 24 will be driven clockwise by gear 22. Miter gear 21 is thus driven clockwise (Fig. 2). Vertical shaft 23 will be driven clockwise worm `gear I1, shaft knife cuts against a hard--v Vtrated in detail because such looking at it in Flgurel. Worm 30 being a left hand worm and being revolved clockwise (Fig. 1), will turn worm gear 3| counter-clockwise. When worm gear 3| is at rest, gears 34 and 35 revolve at the same speed inthe'same direction (counter-clockwise). When 3| is turned clockwise, I find by a study of the epicyclic train of gears 34, 31, 38 and 35v'that gear 35 gets an additional amount of counterclock se rotation and that instead of revolving an amou t equal to 34, it now revolves at a higher speedthan 34 and thus speeds up'II and also |2| 3 and the draw rolls 2, thus pulling up an additional amount of paper while the rest of the machine continues to run at its usual uniform speed. The amount of Y gain in speed of gear 35 is governed'by the prothrough the magnetic clutch. When the holes come in register the light will pass through for a very short space of time, not long enough to cause 'such length of action in the photo-electric cell that the armature would be held up in therelay until the next pair of'holes were in register. The delayin the return of the armature, and hence in the breaking of the electromagnetic clutch circuit is eifectedby the dash pot on the end ofthe armature which is provided with an adjustable release so that the time of dropping of the armature may'be made slow enough to last until the next pair of holes comes into operative position. Thus the circuit will not be broken if the misadjustment of the printed paper should be of suiiicient extent to let the the `current passes .A light through the next pair of holes. In practice majority of the time with occasional rest periods.

A If for some reason (such as shrinkage -of the web) the printed impressions should gain von the machine, the openings come into registry with the holes in the' web and a ray of light passing therethrough will energize the other photo-electric cell amplier relay 62 to close-the line circuit through rings 23' to actuate the clutch -to effect meshing of the reversing and magnetic clutch 4gears 23 and 25 so as to turn worm 3|) in the other direction and rotate worm wheel 3| counter-clockwise (viewed in Fig. 2) which will slow up gear 35 in relation to gear 34 and thus slow up gears II, I2 and I3, rolls 2, and consequently the` printed web in relation to the rest of the machine.

It will thus be seen that the gearing 34,31, 3|, 38, 35 is a change speed gearing operating in such manner that if gear 3| is stationary, both sections of the split shaft I0 rotate at the same speed; whereas if gear 43l is rotated upon operation of the electromagnetic clutch, the section of the shaft carrying the. gear II will travel more rapidly or more slowlythan the other section depending on the direction of rotation of said gear 3|. Obviously. any 'well-known form of change speed gearing maybe associated with the electrically operated clutch, but the gearing ilf lustratedfhas the advantage that the variations in 54 in cylinder 50 will speed are effected gradually and without shock or jar.

The electromagneticclutch has not been illusclutches are Well known and any of a large number of them may suitably be used in. the above machine. ,It will be clear that the clutch is provided with means, such as springs to return the gears 22 and 23 to inoperative position upon breaking of the electric circuits.

While I have shown means controlledby the photo-electric cell for speeding up or slowing down the speed of the rolls 2 to make .correction for the inaccuracies or irregularities explained above, I wish it to be understood it is within the scope of my invention to effect such correction by varying the speed of the cutter at 3 instead of the rolls 2. l5 It is not necessary that a direct ray of light fall upon the photo-electric cells 55 and 56 through holes in the web in order to generate a current therein. Such current may be generated or interrupted by means of a contrasting spot or 20 band or color upon the edge of the web from which light is reflected into the photo-electric cell.v For instance, a black dot or band may be printed on a white web or vice versa, printing instead of punching such web.

It will be clear from the above description that'the length of the cut ol sections of the web vary in length between definite limits and that accumulation of discrepancies is avoided. These limits are governed by the lead or lag of the A30 holes 53, 54 over the holes in the web.

Continuous energization of the photo-electric cell to give the change speed gearing time to act may be effected, and the dash pots dispensed with, by employing an endless belt with holes 35 therein for the escape of a ray of light from a lamp located between the runs of the belt. In this case, the holes in the belt will travel with the holes in the web until, when the change speed gearing has produced the proper correction, the vholes are no .longer in registry. The holes in the belt will be arranged in two series, the holes of each series being spaced the same distance as the holes in the web, but the series being displaced from each other by a distance equal to the permissible variation in the length of the cut sections of the web. y

`It will be clear that the cylinders 49 and 50, and their equivalent, the traveling belt referred to, perform the function of shutters and that instead of such moving cylinders, there may be used stationary boxes for the lamps having an opening controlled by shutters synchronized with the rest of the machine.

I have illustrated .my invention as applied to a 55 paper bag making machine to prevent excessive variation in the feed of a web of paper by a pair of drawing rolls, but it will be clear that my invention may broadlybe employed to control operations in general wherein the character (i. e. 60 color-intensity, etc.) of a ray of light may be varied; for instance, my invention may be employed to detect and correct the lateral shifting of a web or conveyer' belt, such shifting being employed to establish or break the continuity 65 of a ray of light from a source of light to a photo-electric cell; also to detect the presencev of differently colored articles on an opaque carrying surface or of differently colored, translucent or opaque articles' on a transparent carrying sur- 70 face; or to control a machine when an opera- 'l tion, such as drilling or boring, has been completed, thereby permitting a ray of light to pass through the article worked upon; or to discover defects, in the form of holes or variations in 75 opacity, in webs or fabrics whereupon suitable machinery is" operated or regulated. Numerous other applications of my invention will suggestv themselves to those skilled in the art.

Variations may be resorted to within the scope of the claims without departing from the spirit of the invention.

I claim:

1. In a mechanism comprising a device for operating on a web of material, means for continuously advancing said web to said operating device, and electrically operated means for vary- 'ing the speed at which said web is advanced to said source to be projected toward said light controlled devicev at predetermined intervals, said web having. means located in a denite position with relation to each imprint thereon to control l' the passage of light from said projecting device to said light controlled device.

i2. In a mechanism comprising a device to operate on a continuously moving web of material at a predetermined location with relation to each of a series of imprints on said web, and means for normally feeding said web to said operating device with said imprints in proper relation to said operating device, said web having an aperture arranged in deiinite relation to each imprint, mechanism to vary the speed at which said web is fed to said operating device, electrically operated means for controlling said speed varying mechanism, a light controlled device arranged on one side of said web and having means for controlling a circuit for said electrically operated means, a device-arranged on the other side of said web to project a ray of light through an aperture in said moving Web and onto said light controlled device to energize the latter, and means actuated in timed relation to said operating device to so control the passage of light from said projecting device to said light controlled device that said light controlled device will be energized only when said web is in an abnormal position with relation to said operating device.

3. In amechanism comprising a device to operate on a continuously moving web of material at a predetermined location with relation to leach of a series of imprints on said web, and means for normally feeding said web to said operating device with said imprints in proper relation to said operating device, said web having an aperture arranged in denite relation to each'imprint, mechanism to vary the speed at which said web is fed to said operating device, electrically operated means having two separate circuits to control the operation of said speed varying mechanism, light controlled devices arranged on one side of said web and each having means for controlling one of said circuits, light projecting devices mounted on the other side of said web and actuated in timed relation tosaid operating device, said light projecting devices being\so arranged that when the imprint on said web is in one abnormal position with relation to said operating device one of said devices will project a ray of light through anfaperture in said web onto one of said light controlled devices and when said imprint is in another abnormal position with relation to said operating device the other light pro- 60 prints on said web,

the peripheral wall thereof, andY meansv jecting device will project a ray of light through an aperture in said web onto theother light controlled device and 'when said web is in its. normal position with relation to said operating device the apertures therein will be out of line with both light projecting devices.

4. In a mechanism comprising a device to oper.

ate on a web of material at a predetermined location with relation to each of a series of imprints on said web, and means for normally feedingsaid web to said operating device4 with said imprints in proper relation to said operating device, said web having an aperture arranged in deiinite relation to each imprint, mechanism to vary the speed at which said web is fed to said operating` device, electrically operated means for controlling said speed varying. mechanism, alight controlled` device arranged on one side of said web and having means for controlling a circuit for said electrically operated means, a lamp arranged on the other side oi' said web I throughv an :aperture in said web onto s aid light controlled device, anda device actuated in timed relation to said operating device and having a part interposed between said lamp and said web and provided with an opening arranged 'to register with an aperture in said web when the imprint on said web is in an abnormal position with relation to said operating device.

,5. In a mechanism comprising a device to operate on a continuously moving web oi material at a predetermined location with relation to each of a series of imprints onsaid web, and means for normally feeding said web to said operating device with said imprints in proper relation to said operating device, said web having an aperture arranged in definite relation to each imprint, mechl anisrn to vary the speed at which said web is fed to said operating device, electrically operated 40 means having two separate circuits to control the operation of said speed varying mechanism, light controlled devices arranged on one side of said web and each having means for controlling one y of said circuits, light projecting devices mounted 46 on the other side of said web and actuated in timed relation to said operating device, said light projecting devices being so arranged that when'an imprint on saidgweb is in one position with relation to said operating device one of said devices 50 will project a ray of light through an aperture in said web onto one of said light controlled devices and when said imprint is in another position with relation to said operating device the other light projecting device will project a ray of light 56 through an aperture in said web onto the other light controlled device. l

6. In a mechanism comprising aidevice to operate on a web of material at a predetermined location with relation to each of a series of imand means for normally feeding said web to said operating device with said imprints in proper relation to said operating device, saidweb having an aperture arranged in deiinite relation to each imprint, mechanism to vary the speed at which said web is fed to said operating device, electrically operated means hav-V ing separate circuits and adapted to initiate and interrupt the operation of -said speed` varying mechanism,llight controlled devices arranged on one, sideof said web and each having means for controlling one' of said circuits. light projecting devices mounted on the other side oi' vsaid web and actuated in timed relation to said actuating device, each light projecting device comprising a hollow rotatable member having an opening in to project a ray-of lightV for projecting a ray of light through' said opening, and said opening being so arranged that it will register with an aperture in said web when the K' imprint on said web is in a predetermined position with relation to said operating device, and thereby cause said ray of light to pass through said aperture onto one o! said light controlled devices.

7. In a mechanism comprising a device for operating on a web of material, means for continuously advancing said web to said operating device, and electrically operated means for varying the speed at which said web is advanced to control the position of an imprint on said web with relation to said operating device, a iight controlled device arranged on one side -of said web and having means to control a circuit for said electrically operated means, a source of light arranged to project light toward that side of said web opposite said light controlled device, and a device operated in timed relation to said operatingl device to cause light from said source to be projected toward said web at predetermined intervals, said web having means located in a dennite position with relation to each imprint thereon to control the passage of light from said source to `said light controlled device.

il.l In a mechanism comprising a device for operating on a web of material, means for continuously advancing said web to said operating device, and electrically operated means for varying the speed at whichsaid web is advanced to control the position of an imprint on said web with relation to said operating device, alight controlled device arrangedon one side of the path of said webl and having means to control a circuit for said electrically operated means, and light projecting means arranged on the other side of the path of said web and comprising a source of light, and a device actuated in timed relation to said operating' device and having a part arranged to i move between .said source oi light and said web and to cause light from said source to `be projected onto said web at intervals, said web having means located in a definite position with relation to each imprint thereon to control the passage oi light from said projecting device to said iight controlled device.

9. In a web feeding mechanism having electrically operated means for controlling the position o! an imprint on said weiwith relation to a device which operates on said web, a light controlled device arranged on one side of said-web and having means to control a circuit for said electrically operated means, a Lamp arranged on the other side of saidweb, and a device mounted for rotation in timed relation to said operating device and having a part interposed between said lamp and said web and provided with an opening throughwhich light from said lamp may be projected onto said light controlled device, said web having means arranged in definite relation to each imprint thereon to control the passage of light from the opening in said rotatable device to said light controlled device;

10. In a web feeding mechanism having electrically operated means for controlling the position of an imprint on the web with relation to a device which operates on' said web, detecting errors in the feeding of said web comprising a light controlled device arranged on one side of said web and 'having means to control a circuit for said electrically operated means. a hollow element mounted on the other side of said web for rotation at a constant speed and having a. device for an opening arranged to move over said w'eb `as said hollow element rotates, and means mounted within said hollow element for projecting a ray of light through said opening, said web' having means arranged in deilnite relation to each imprint thereon to control the passage of light from said opening to said light controlled device.

11. In 'a web feeding mechanism having electrically operated means for controlling the position of an imprint on the web with relation to a device which operates on said web, a device for detecting errors in the feeding of said web comprising a light controlled device arranged on one side of said web and having means to control a circuit for said electrically operated means, a hollow element mounted on the other side of said web for rotation at a constant speed and having an opening arranged to move over said web as said hollow element rotates, and means mounted within said hollow element for projecting a ray of light through said opening, said web having an aperture arranged in a definite position with relation to each imprint and adapted to register with said opening when the imprint on said web assumes an inaccurate position with relation to said operating device.

12. In a web feeding mechanism having elec-,

trically operated means for controlling the position of anlimprint on said web with relation to a device which operates on said web, a device for detecting errors in the feeding of said web comprising light controlled devices arranged on one side of said web and'having means for controlling circuits for said electrically operated means, hollow elements mounted on the other side of said web, spaced apart in the direction of movement of said web and havingl openings arranged to move over said web as said hollow elements rgtate, and means within each hollow element to project a ray of light through the opening therein, said web having means arranged in definite relation to each imprint thereon to control the passage of light from the openings in said rotatable elements to said light controlled devices.

13. In a web feeding mechanism having electrically operated means for controlling the position of an imprint on said web with relation to a device which operates on said web, said web having an aperture arranged in deilnite relation to each imprint thereon, a device for detecting errors in the feeding of said web comprising light controlled devices arranged on one side of said web and having means for controlling circuits for said electrically operated means, hollow ele- 5 ments mounted on the other side of said web for rotation in timed relation to said operating de- Vice and having openings arranged to move over said web as said` hollow elements rotate, and means within each hollow element to project a ray .of light through the opening therein, the openings in said elements being so arranged with relation one to the other and tosaid operating device that when an imprint on said web assumes a position in the rear of its normal position the adjacent aperture will register with the opening in one of said rotatable elements, and the light from said opening will be projected through said aperture toward one of said light controlled devices, and when an imprint on said web assumes a position in advance of its normal position the adjacent aperture will register with the opening in 'the other of said rotatable elements and the light from that opening will be projected toward the other of said light controlled devices.

14. In a machine having a device to operate on a web oi' material at a predetermined location with relation to each of a series of imprints on said web, means for feeding a web to said operating device, driving mechanism for said operating device and said feeding means, a device to vary the speed at which said web is fed to said operating device, means including a clutch to operatively connect said speed varying device with said driving mechanism, electrically operated means to actuate said clutch to first establish said connection and to then interrupt the same, and means controlled by the position of the imprints on said web with relation to said operating device to control the circuit for said electrically operated means.

15. In a mechanism comprising a device 4to operate on a web of material at a. predetermined location with relation to each of a series of imprints on said web, and means for normally feeding said web' to said operating device with said imprints in proper relation to said operating device, said web having an aperture arranged in definite relation to each imprint, normally inoperativemeans for varying the speed at which said web is fed to correct variations in the position of said imprints with relation to said operatf ving' device, electrically operated means to control the operation of said speed varying means and having separate circuits, and a detector compris- `ing two parts adapted to separately operate n tain the same closed independently of said detector, said parts of said detector being so arranged that one of said parts can operate through an aperture in said web only when the imprint on said web is in the rear of its normal position and the other of said parts can operate through an aperture in said web only when said imprint is in advance of its normal position.

16. In a web feeding mechanism having electrically operated means for controlling the position of imprints on said web with relation to a device which operates on said web, a source of light, a device mountedfor movement in timed relation to said operating device and having a part interposed between said source of light and said web to cause vlight from said source to be projected toward said web at intervals, and a light controlled device arranged to receive light from said source and having means to control a circuit for said electrically operated means, said web having means associated with the imprints thereon to control the passage` of light from said source to said light controlled device.

17. Ina web feeding mechanism having electrically operated means for controlling the position of imprints on said web with relation to a device which operates on said web, a source of light. a device mounted for rotation in timed relation to said operating device and having a part interposed between said source of light and said web and provided vwith an opening through which light from said source may be projected toward said web at intervals. and a light controlled device arranged to receive light from said opening and having means to control a circuit i'or said electrically operated means, said web having means Iassociated with the imprints thereon to control the passage of light from said opening to said light controlled device.

, 18. In a web feeding mechanism having electrically operated means for controlling the position of imprints on said web with relation to a device which operates on said web, a light proy 50 tinuously jecting device comprising a source of light, and a hollow element mounted about said source of light for rotation at a constant speed and having an opening arranged to move over said web as said hollow element rotates to cause light from said source to be projected toward said web vat intervals, and a light controlled device arranged to receive light from said projecting device and having means for controlling a circuit for said electrically operated means, said web having means associated with the imprints thereon to control the passage of light from'said light projecting device to said light controlled device.

19. In a mechanism comprising a device for operating on a web of material, means for advancing said web to said operating device, electrically operated means for varying the speed at which said web is advanced to control the position of imprints on said web with relation to said operating device, a continuously illuminated source of light, meansv for causing a ray of light to be projected from said source toward said web at predetermined intervals, and a light controlled device arranged to receive light from said source and havingl means 'to control the circuit for said electrically operated means, said web having means associated with said imprints thereon to control the passage of light from said source to said light controlled means.

20. In a mechanism comprising a device for operating on a web of material, means for continuously advancing said web to said operating device, electrically operated means for varying the speed at which said web is advanced to con- A trol the position of the imprints on said web with relation to said operating device and comprising two circuits, means for projecting 'two separate rays of light toward s aid web at predetermined intervals and at different times with 40 relation to the operation of said operating device, and two light controlled devices arranged tol receive the respective rays of light and having means to control the respective circuits, said web having means associated with the imprints `4:5" thereon to control the passage of said rays of light from said projecting means to said light controlled device. r l

21. In a mechanism comprising a device for operating on a web -oi material, means for conadvancing said'web to said operating device, electrically operated means for varying the speedatwhich lsaid web is advanced to control the position 'of imprints on said web with relation `to said operating device, means for projecting a ray of light toward said moving web at predetermined intervals, and` a light controlled device arranged to receive said ray of light and having means to control said electrically operated means, said ray of light constituting lthe sole means for controlling said light controlled device, and said web having means associated with the imprints thereon to control the passage. of said -ray of light from said projecting means to said light controlled device. i

Z2. In a mechanism-comprising a device for operating on a web of' material, means for continuously advancing said web to said operating device, and means for varying the speed at which said web is advanced to control the position of an imprint on said web with relation to said operating device, an electro-magnet to control the operation of said speed varying means, a source of light, a device operated in timed relation to said operating device sourceto be projected to cause light from said toward said web at predetermined intervals, and a light controlled der vice arranged to receive light from said source of light and having means to control the energization of said electro-magnet, said web having means associated with each imprint thereon to control the passage of light from said source to said light controlled device.

23. In a web feeding mechanism, means for vcontinuously advancing the web, means 'including an electric circuit for controlling the speed at which said web is advanced, a continuously illuminated source of light, means for causing light from said source to be projected toward said web at predetermined intervals, and a light controlled device arranged'to receive light from said source and having 'means for controlling said circuit,

said web having means for controlling the passage of light from said source to said light controlled device.

24. In a web feeding mechanism, means for continuously advancing a web having a series of imprints thereon, means including two electric circuits for controlling the speed at-which said web is advanced, means for projecting two separate rays of light toward the moving web at predetermined intervals and at 'diierent times, and light controlled devices arranged to receive the respective rays of light and having means i for controlling the respective circuits, said-""web having a single means associated with each imprint/thereon and arranged for movement successively into positions to control the passage of the respective rays of light to said light controlled devices.

. HAROLD SMITHWICK. 

